Furry foes
The commercial trapping of animals to turn their pelts into fur coats can never be justified (14 December 2002, p 13).
It is true that the introduction of the brushtail possum to New Zealand is one of the country’s greatest ecological disasters. The species is greatly modifying New Zealand’s ecosystem, in some areas causing total canopy collapse and local extinctions.
What wasn’t mentioned in the article was the fact that it was the fur trade that deliberately introduced the possum to New Zealand to provide future profits. Tragically, this is not an isolated incident.
North American mink were deliberately introduced to many parts of Europe with the intention of establishing wild populations that could subsequently be trapped. The impact on native fauna due to predation and competition has been devastating.
Here in Britain, mink became established not by deliberate release but by the irresponsibility of fur breeders who allowed the animals to escape. As a result, many breeding bird populations are threatened, and the mink has contributed to the decline of the water vole 鈥� the most rapid and serious decline of any British wild mammal in the 20th century.
Introductions of the coypu are causing significant wetland damage. In coastal Louisiana, for instance, coypu activity is now believed to affect 100,000 acres of globally important marsh vegetation, with serious implications for a number of endangered species. The semi-aquatic muskrat, the raccoon and the raccoon-dog have also been introduced by the fur trade to various parts of the world where they wreak havoc.
None of these species chose to be introduced to alien habitats, yet it is they who are now being persecuted (often at the taxpayer’s expense) by trapping and poisoning. Having profited from this environmental carnage, surely it is the fur trade that should now pay to fix it, and not be encouraged to profit further at the expense of the animals.
If urgent action is required to maintain biodiversity, trapping (suggested by fur traders) or poisoning are clearly not the only options. There are far more civilised methods such as humane capture and re-release, or contraceptive methods as your article suggested.
Rivers of dust
The news piece about asteroid impacts on Mars perpetuates the myth that only water could have produced the channel-like features we see on the surface of the planet (14 December 2002, p 22, and p 15, this issue).
These channels have clearly been scoured by a flowing medium, but this does not have to be water. A very likely alternative is turbidity currents. These occur when a volume of a medium such as air or water is heavier than the surrounding medium because of suspended particles. Examples on Earth include avalanches, volcanic ash flows, and, in the deep oceans, turbidity currents 鈥� flows of suspended sediment.
Detailed images of ocean floor channels are much more similar to the pictures of Mars than any river system. Mars has all the requirements for turbidity currents. Billions of years of meteorite bombardment have produced thick layers of fine dust. The well-documented dust storms and dust devils move this dust to higher areas, where it can become suspended in the atmosphere and flow downhill as a turbidity current, eroding into the soft surface to create the meandering channels.
The absence of water on Mars will help this process, because the fine dust will not be stabilised by ground water, as happens on Earth. Another factor may be Mars’s low gravity, which slows the settling out of suspended dust particles.
Thus the formation of channels is an ongoing process, which explains why the channels are usually younger than the surrounding craters. It also explains the “ocean-like” appearance of the lowest parts of Mars: they have been filled in by the dust from turbidity currents.
The turbidity-current idea has the advantage that it only involves known sedimentation processes and does not require difficult, far-fetched theories about large amounts of water once being present on Mars. Such theories are too much driven by the wish that there once was water on Mars, and hence, possible life there.
Need for scepticism
Fred Hoyle maintained that heterodoxy was the duty of all scientists. Karl Popper insisted that science prospered within a community of scepticism.
It is revealing, as well as depressing, to note how frequently environmental scientists, especially the ideologues of climate change, appeal to “scientific consensus” to gain credence for their inadequate theories.
Kurt Kleiner (4 January, p 21) seems now to oppose the Bush Administration’s programme to expose these nostrums to sceptical appraisal and peer review. His is the method of faith, not science.
No such spider
I read with surprise the mention of a giant Carboniferous fossil spider with a leg span of 50 centimetres (14 December 2002, p 42). The species in question was described in 1980 as Megarachne servinei (not Megaranea as cited in your article) from a single fossil specimen found in Argentina. It was placed in the new family Megarachnidae in the suborder Mygalomorpha, which includes the large, hairy, so-called tarantulas and bird-eating and baboon spiders.
However, the taxonomic classification of this species has never really been accepted. The specimen does not show any of the phenotypic characters diagnostic of spiders. And in 2001 a reanalysis of the original specimen and data from a second well-preserved fossil found in the same area suggested that the fossils were very different from other arachnids, and proposed that the specimen may belong in a new order of fossil arachnids.
There is certainly unequivocal evidence of giant insects in the fossil record. However, as yet the same is not true for spiders.
Fire-safe cigs
We thought it was pretty well known that manufactured cigarettes contain an additive specifically to ensure a lit cigarette does not self-extinguish (21/28 December 2002, p 6). Also, that hand-rolled ones go out if left unpuffed for several seconds, because they’ve not got it.
So why did the article mention the idea of using, for example, “low porosity paper” when there is no need for it? Just leave out the additive. All cigarettes would go out quickly when dropped, discarded, or not puffed frequently, and users would smoke less 鈥� Oh, I see now.
Glaring problem
Wendy Wolfson’s article on a new outdoor lighting technology rather got my back up (21/28 December 2002, p 58). A few years back I noticed that fancy Christmas lights were becoming popular on the outside of British houses and in gardens. My own family call me scrooge, but the fact is that light pollution is making serious amateur astronomy more and more difficult. Believe it or not, some people still want to see the real stars.
Ratio that pleases
Marcus Chown dismissed the aesthetic qualities of phi too quickly (21/28 December 2002, p 55). While it is clear that a particular shape may not always please, one quality does seem to be intrinsically recognisable, in the visual arts as well as in music, namely ratios.
The great advantage that phi offers us, architects especially, is the facility to repeat ratios that are neither boring nor increase too rapidly. Le Corbusier certainly made good use of two specific sets of dimensions based on the Fibonacci series. English Georgian architects knew it well. Measure any of their standard terraces 鈥� the dimensions of the windows, the spaces between, the shape of the whole 鈥� and you will find phi everywhere.
You will rarely find it in any modern building, though. Modern standardisation does not bother with proportion.
Pluto's hot rocks
Your box about Pluto experiencing a global warming episode did not take into account the energy release time, or thermal conductivity, of its rocky surface (14 December 2002, p 33).
The two estimates of the atmospheric density, and hence the surface temperature, were based on light from stars occulted by Pluto in 1988, one year before the planet’s closest approach to the Sun, and in 2002, 13 years after its closest approach to the Sun. The second measurement produced the slightly higher temperature estimate, which surprised many scientists.
Pluto’s rocks take time to heat up, as well as time to release the heat they contain back into the thin nitrogen atmosphere. This may be the cause of the observed increase in temperature. As an analogy, if you measure the temperature of a mass of rock in a desert just before noon (equivalent to Pluto’s closest approach to the Sun) and again a few hours later, you will find the rock is hotter in the afternoon measurement.
Fear, not empathy
Your article on why children take a long time to grow up cites the fact that “babies will start to cry when they hear other babies in distress” to support the hypothesis that infants have some degree of empathy (7 December 2002, p 44).
This conclusion ignores other possibilities 鈥� for example, that hearing screams might make a baby uncomfortable or even afraid. Discomfort and fear are, in my book, more plausible causes for a baby’s cries than empathy.
Hot head
Your research on the decay rates of the heads of beer missed one of the most important variables 鈥� the temperature of the glass (21/28 December 2002, p 66). The warmer the glass the faster the decay.
On holiday in Britain several years ago I was somewhat disappointed with the heads on the beers until I realised that the glasses in bars and pubs there are stored on a shelf at room temperature. Any Aussie beer drinker will tell you that a decent head can only be achieved in a chilled glass, and the colder the better.
Many years of research have revealed that the reduction of the level of the liquid does not follow a similar curve. However, I’m too busy conducting further tests to publish.
Miserable models
I was alarmed to see that one of the winners in the Feedback Christmas Competition advanced a very unorthodox view of evolutionary theory in their explanation of the moodiness of models (21/28 December 2002).
If sacrificial virgins of ancient times had worn an understandably glum expression, this behaviour could not have been passed on to their offspring, since they could not have had any.
And if the sacrifice was only symbolic, and the beautiful virgins went on to lead full reproductive lives, by what mechanism would their sullen demeanours have been propagated? This sounds suspiciously Lamarckian to me!
However, if being miserable meant that beautiful girls would not be chosen for sacrifice 鈥� too mopey for the gods, perhaps 鈥� then this might offer a plausible evolutionary advantage for glumness in beautiful young women. This after all might explain the apparent unhappiness of models at fashion shows.
For the record
鈥� In the article revealing higher than expected cadmium toxicity in soil (21/28 December 2002, p 14), we mistakenly stated that in the 1950s, hundreds of Japanese were poisoned by cadmium pollution in Yokkaichi, 300 kilometres south-west of Tokyo. In fact, most of the victims were in Toyama, 300 kilometres north-west of Tokyo.